UBRARIES Dedication In memory of

For impressing upon me their appreciation of nature and the importance of critical thinking, I dedicate this thesis to my late grandfathers: Lawrence Silas Carr and Dwight Herrick Macduff. I also thank my living family members for being patient with me and forgiving my forgetfulness of birthdays and other special occasions during these seven:years at MIT. I have been influenced by a great number of excellent teachers who believed in me and pushed me to excel beyond what I imagined possible. Most notable for my scientific and analytical development are my human-genetics high-school teacher, Mr. Gordon Mendenhall; Mr. Dan Stiko, high-school teacher of several math courses; my undergraduate mentor, Professor Douglas Cavener; and, of course, my graduate advisor, Dr. Peter Kim. Toward my personal growth, I am indebted to my high-school choir and dance director Ms. Sandra Butz; Mr. Gary Meyers, my high-school theater director, and Mr. Michael Kim Howden, junior-high world-history teacher, enduring friend, counselor, and confidant. The best years of my life have been spent in the exhilarating environment of MIT and the Whitehead Institute. The friends and colleagues I have met here I will treasur